Apparatus for making cellular structures

ABSTRACT

Apparatus for making a cellular structure having a plurality of walls extending along intersecting planes and together providing abutting cells, such walls being connected at their locations of intersection by cruciform sections and formed by flexing portions of a slit web material into planes disposed at angles to the plane of the original web material.

y 1972 T. H. FAIRBANKS 3,676,267

APPARATUS FOR MAKING CELLULAR STRUCTURES Original Filed March 19, 1968 2Sheets-Sheet 1 y 11, 1972 T. H. FAIRBANKS 3,676,267

APPARATUS FOR MAKING CELLULAR STRUCTURES Original Filed March 19. 1968 2Sheets-Sheets United States Patent 3,676,267 APPARATUS FOR MAKINGCELLULAR STRUCTURES Theodore H. Fairbanks, Liverpool, Pa., assignor toFMC Corporation, Philadelphia, Pa.

Original application Mar. 19, 1968, Ser. No. 714,231,

now Patent No. 3,616,025. Divided and this application July 21, 1970,Ser. No. 56,815

Int. Cl. B32b 31/18 U.S. Cl. 156523 3 Claims ABSTRACT OF THE DISCLOSUREApparatus for making a cellular structure having a plurality of wallsextending along intersecting planes and together providing abuttingcells, such walls being connected at their locations of intersection bycruciform sections and formed by flexing portions of a slit web materialinto planes disposed at angles to the plane of the original webmaterial.

This application is a division of my application Ser. No. 714,231, filedMar. 19, 1968, now U.S. Pat. No. 3,616,025.

The invention relates to apparatus for making articles of cellularconstruction.

Members of cellular, and more particularly of honeycomb construction,are light in weight and provide substantial structural volume, rigidityand strength for the relatively small amount of material used in theirconstruction. Such honeycomb members have, therefore, found wideapplication in many fields, as for example, loadbearing floors,ceilings, and walls; as reinforcing cores or panels in flush doors; asrigid article separators or spacers; as grilles or screens for suspendedceilings and light fixtures; etc.

Honeycomb structures can be manufactured by a variety of known methods.Perhaps one of the most common methods in'vol-ves interlocking ofslotted strips or slats in crossing relationship. In another knownprocedure, strips of suitable material are bent, with sharp corners,into a corrugated form and then connected to each other in sideby-siderelationship to provide a series of abutting cells. These and otherknown methods for making honeycomb structures often require expensivematerials, generally involve a number of machining steps and/ ormanipulations of the different members during assembly and are usuallynot suited for rapid manufacture of continuous cellular or honeycombstructures. Accordingly, a primary object of this invention is toprovide a generally new or improved and more satisfactory apparatus formaking cellular or honeycomb structures.

Another object is the provision of an improved apparatus for making ahoneycomb structure which is light in weight, possess good structuralvolume, rigidity and strength and can be made from inexpensive materialsand with low manufacturing costs.

A further object is to provide an improved apparatus for making ahoneycomb structure from a continuous traveling web material.

A still further object is the provision of an improved apparatus formaking continuous honeycomb structures rapidly and at low costs.

These and other objects are accomplished in accordance with the presentinvention by an apparatus in which a pliable web material is slit alongonly a portion of the length of each of a series of lines defining aplurality of abutting parallelograms, with adjacent parallelogramsabutting along a common line. The slits of the individual parallelogramsmeeting or intersecting at only one pair of diagonally opposed cornersthereof and terminating 3,676,267 Patented July 11, 1972 ice short oftheir other pair of diagonally opposed corners. Thus, ends of such slitsare separated by narrow neck sections of web material. Each of theportions of the web material extending between these neck sections isthen pivoted as a planar unit by flexing or twisting the web material inthe areas of the neck sections into a helical configuration. The freecorners of the individual parallelograms; that is, the diagonallyopposed corners thereof at which the slits meet, are thus moved inopposite directions away from the plane of the original Web material.

As noted above, the web material must be pliable to permit the necksections thereof to be flexed or twisted into helical shapes withouttearing. A variety of web materials may be employed in making thecellular structures with the apparatus of the present invention,including materials which are thermoplastic, such as polyamides orsuperpolyamides, polyesters, polyvinyl chlorides, and copolymersthereof, polyolefins, and cellulose acetates; thermosetting materials;metals, such as aluminum, copper, brass, sheet steel; papers; fabrics;and etc.

With the exception of the Web materials formed of ductile metals, it isgenerally necessary to set the pivoted portions of the web material tofix the same in position. Thus, with web materials which are ofthermoplastic character, the portions of the web material which extendbetween the neck sections may be in a heat-softened condition Whilebeing pivoted and then cooled to set the same in fixed positions.Thermosetting web material may, of course, be set by heat, whilematerials, such as paper or fabrics may be fixed by the application ofcoatings capable of being hardened or otherwise stabilized.

The slits formed in the web material must together define a plurality ofabutting parallelograms; that is, with adjacent parallelograms abuttingalong a common slit.

-The lengths of the neck sections of web material between the ends ofthe slits must be such as to permit the same to easily flex or twist asthe portions of the web material extending between such neck sectionsare pivoted as planar units. The lengths of these neck sections of webmaterial will depend, to some degree, upon the particularcharacteristics of the web material employed.

In honeycomb structures intended primarily for decorative applications,such as screens or grilles, the slits formed in the web material may besuch as to define parallelograms of different sizes. If further desired,the portions of the web material extending between the neck sectionsthereof may be pivoted, as planar units, to different degrees relativeto the original plane of the web material.

Honeycomb structures which possess substantial strength and rigidity areformed by initially providing a web with slits which are of equallength, and preferably extend at right angles to each other. Theportions of the web material extending between the neck sections thereofare then pivoted, as planar units, through an angle of from the originalplane of web material and, if necessary, set in such positions.

The cellular or honeycomb structure produced by the apparatus of thepresent invention includes a series of walls extending along each of aplurality of planes which intersect with each other, with sections ofcruciform configuration integrally connecting the walls to each other atthe locations of intersection of their respective planes. Thesecruciform sections each have a central portion, disposed in a planeextending at an angle to the planes of the series of walls, and legs ofhelical shape extending between the central portion of the cruciformsection and the walls adjacent thereto. Desirably, the central portionsof the cruciform sections are disposed in a plane which is substantiallyperpendicular to the planes of the series of walls, and the wallsthemselves are preferably located along planes which intersect atsubstantially right angles with each other.

Structures of still greater strength and rigidity than those heretoforedescribed are provided by attaching a continuous sheet, web material orother flat member to at least one and preferably both sides of thehoneycomb structure to thereby form a composite product. Attachment ofsuch continuous sheets may be effected by projecting the free corners ofthe pivoted portions of the web material through suitable slots formedin the sheets themselves. These projecting corners are then distorted,as by bending, twisting, or are heat-softened to lock the sheets inplace.

An alternative procedure for making a composite product using thehoneycomb structure as a core entails re moving the free corners of theportions of the web material supported between the neck sections priorto pivot ing of such portions. Such free corners may be removed bycutting the same along lines extending generally perpendicular to a lineextending between such free corners. The edges thus provided will extendgenerally parallel to the original plane of the web material after theportions of the web material extending between the neck sections arepivoted into planes substantially perpendicular to their originalplanes. A continuous sheet, web material or other flat member is thenfixed to these edges of the pivoted portions of the web material, as byadhesives, heat, etc.

In the composite products described, it will be apparent that the sheetsfixed to the honeycomb structure maintain the pivoted portions thereofin the fixed positions. Moreover, such attached sheets serve also todistribute loads over a large area of the composite product and, ifdesired, may be made fluid-tight to impart bouyant and perhapsheat-insulating characteristics to such products.

The continuous sheets or other flat members of the composite productsdescribed above may be formed of any desired materials and may be thesame or different from that of the honeycomb structure itself. Suchsheets may include various additives, such as colorants, stabilizers,etc., if desired or necessary and, in the case of plastic materials, maybe of transparent or translucent character.

The apparatus of the present invention includes means for providing apliable web material with closely-spaced rows of cross-cuts in which thecross-cuts of alternate rows are located between the ends of cross-cutsin the rows adjacent thereto, a first and second series of pyramidshapedprojections for engaging with opposite sides of the web material,respectively, at the locations of the cross-cuts, with the projectionsof two series thereof being in staggered relationship, and means formoving the first and second series of projections toward each other andthrough the web material to thereby deflect portions thereof from theiroriginal plane. Preferably, the apparatus is designed for continuousmanufacture of honeycomb structures. Thus, the means for cutting the webmaterial as well as the two, series of projections are carried bysuitable rollers or belt conveyors so as to permit the same to performtheir intended operations on a web material concomitantly with itscontinuous travel.

To facilitate the manufacture of composite products of the character asheretofore described, the apparatus also includes, in one embodiment,means for providing a continuous sheet with slits at spaced locationscorresponding with the spacing of the deflected portions of the webmaterial, means for disposing the slit sheet onto the deflected portionsof the web material so that such portions project partially through theslit sheet, and means for distorting the projecting parts of thedeflected portions of the web material to thus lock the sheet in place.

In another embodiment, the apparatus of the present invention alsoincludes means for cutting the web along lines extending betweenadjacent slits of each of the crosscuts, to thereby remove a rectangularsection of web ma- 4 terial therefrom, and means positioned beyond theseries of projections for attaching a continuous sheet to the outermostedges of the deflected portions of the web material.

In the drawing,

FIG. 1 is a diagrammatic side view of the apparatus of the presentinvention;

FIG. 2 is a plan view of a portion of a web material following aslitting stage by the apparatus shown in FIG.

FIG. 3 is a fragmentary plan view of a portion of the apparatus shown inFIG. 1;

FIG. 4 is a view similar to FIG. 1 showing a portion of the apparatus onan enlarged scale and illustrating its operation;

FIG. 5 is a plan view of a portion of a honeycomb structure producedwith the apparatus of the present invention;

FIG. 6 illustrates a cellular or honeycomb structure, as produced withthe apparatus of the present invention, employed as a core of acomposite product;

-FIG. 7 is a view similar to FIG. 5 showing a composite product ofmodified construction;

FIGS. 8 and 9 are views similar to FIG. 2 showing web materials withmodified arrangements of slits.

With reference to FIG. 1 of the drawing reference character 15 indicatesa continuous web material and particularly a thermoplastic film, such asof polyethylene, which is drawn from a suitable source and shaped into acellular or honeycomb structure as it is continuously advanced throughthe apparatus of the present invention. Upon entry into the apparatus,the film 15 passes between a cutter roll 17 and a back-up roll 19 whichtogether provide the film with rows of cross-cuts 21. As shown in FIG.2, the cross-cuts 21 in alternate of such rows are located between theends of the cross-cuts 21 in the rows which are adjacent thereto.

The cross-cuts 21 each consist of four individual slits 23, 25, 27 and29. These individual slits of the different cross-cuts 21 extend alongonly a portion of the length of each of a series of lines which togetherdefine a series of abutting parallelograms or square portions 31. Ineach of these square portions 31, the slits forming the same meet orintersect at only one pair of opposed corners thereof. At the other pairof such opposed corners thereof, the individual slits terminate justshort of each other and are separated at their ends by narrow necksections 33.

If desired, a square segment 35 of the film 15 is removed from thecenter of each of the cross-cuts 21, preferably simultaneously with theformation of such crosscuts. The edges 37 provided by the removal ofthese square film segments 35 extend substantially perpendicular tolines drawn between opposed corners of the square portions 31 and afterfilm shaping, as hereafter described, will be in planes which areparallel to the original plane of the film.

Upon the movement of the film 15 beyond the rolls 17 and 19 it isimpinged along its opposite sides by hot gases delivered by nozzles 39,and then advanced in between a a pair of endless belts 41 and 43, bothof which include a series of truncated, pyramid-shaped projections 45.The hot gases which are discharged from the nozzles 39 are not intendedto melt or cause undesired flow of the film material but merely softenthe same.

The endless belt 41 is laced over drums 47 and 49, at least one of whichis driven in the direction of arrow 51. The belt 43 is likewise lacedover drums 53 and 55, at least one of which is driven in the directionof arrow 57. Between the reaches of the respective belts 41 and 43 aredisposed nozzles 59 for directing cool air against reaches of the belt43 are longer than that of the belt the opposing belt reaches and theportion of the film therebetween. For purposes as described hereafter,the

41 and thus its uppermost reach is supported against sagging by a fixedtable 60.

As shown in FIG. 3, the projections 45 of the belt 43 are positioned toengage with one side of the film at the locations of the cross-cuts 21in alternate longitudinally extending rows thereof. Further, it will benoted that the projections of the belt 43 are each disposed so that thecorners thereof will be aligned with the slits of the cross-cuts.

As each of these projections 45 of the belt 43 move into engagement withone side of the film 15, four of the portions 31 are simultaneouslypivoted as planar units about their respective neck sections 33 and areurged toward positions as shown in FIG. 4. The projections 45 of thebelt 41 are intended to engage the opposite side of the film 15, butonly at the locations of cross-cuts 21 which are not engaged byprojections 45 of the belt 43. Thus, the projections 45 of both belts 41and 43 together cooperate in pivoting the film portions 31 and inmaintaining the same in vertical planes, as shown in FIG. 4, as they areadvanced relative to the nozzles 59 where they are cooled and set inplace.

The cellular or honeycomb structure 61 which is produced may be thenremoved from between the belts 41 and 43. In such structure, as shown inFIG. 5, the portions 31 of the original film 15 extend along planeswhich intersect each other at substantially right angles. Between suchportions 31 are cruciform sections 63, each of which includes a centralportion 65 and legs 67 of helical configuration. The central portions 65of the cruciform sections all lie in a plane which is substantiallyperpendicular to the planes of the portions 31. The helical shaped legs67 are, in effect, the film neck sections 33 after they have beentwisted during the pivoting of the portions 31. 1% In lieu of removingthe honeycomb structure 61 from the apparatus, continuous sheets orfilms 69 may be attached to one and preferably to opposite sides thereofto provide a composite product 71 as shown in FIG. 6. As heretoforementioned, square segments 35 of the film 15 need not be removed and insuch instance the free corners of the film portions 31 will appear inthe resulting honeycomb structure 61 at locations between the cruciformsections 63. The films 69 may therefore be slit at 73 to receive thecorners of the portions 31 of the structure 61 and then be bent over asshown at 75 to lock the films 69 in place.

On the other hand, with removal of the square film segments 35, the film69 may be attached to the edges 37 of the portions 31 of the resultinghoneycomb structure 61 to provide a composite product 77 as shown inFIG. 7. More particularly, and as shown in FIG. 1, a film 69 may beguided about a roller 79 and laid onto the uppermost surface of thehoneycomb structure 61. As such honeycomb structure 61 and film 69 aretogether carried continuously by the upper reach of the belt 43, thefilm 69 is softened by a heater 81 and then cooled by air from a nozzle83 and thereby bonded in place.

A film 69 may be bonded to the underside of the honeycomb structure 61in a like manner after such structure moves beyond the belt 43. As shownin FIG. 1, this film 69 is guided by roller 85 against the underside ofthe honeycomb structure 61, softened and pressed by a heater 87 and thencooled as by air from a nozzle 89. A backup plate 91 is providedoppositely of the heater 87 to prevent upward movement of thecompositive structure in this area.

In making the honeycomb structure 61, the slits 23, 25, 27 and 29 of thecross-cuts 21 in the formed film 15 are of substantially the same lengthand extend along planes which intersect at substantially right angleswith each other. While the honeycomb structure which is provided, asshown in FIG. 5, is of a preferred construction, the apparatus of thepresent invention is also applicable to making honeycomb structureshaving different cell arrangements. Thus, as illustrated in FIG. 8, afilm 91 may be provided with cross-cuts 93 in which the slits thereofextend along planes which intersect at angles other than right angles. Afurther alternative is shown in FIG. 9 wherein a film 95 is providedwith cross-cuts 97, each of which includes three slits 99, 101 and 103which are of like size and shorter than the slit 105. The slit films 91and 95 shown in FIGS. 8 and 9, respectively are shaped into honeycombstructures in the same manner as heretofore described.

It is to be understood that changes and variations may 'be made withoutdeparting from the spirit and scope of the present invention as definedin the appended claims.

I claim:

1. Apparatus for making a cellular structure including means forproviding a pliable web material with closelyspaced rows of crossingslits in which the crossing slits of alternate rows are located betweenthe ends of crossing slits in the rows adjacent thereto, a first andsecond series of pyramid-shaped projections positioned to engagerespectively, with opposite sides of the slit web material at thelocations of the crossing slits, the projections of said first seriesbeing in staggered positions relative to the projections of said secondseries with corners of each of said projections being oriented to alignwith crossing slits in the web material, and means for simultaneouslymoving the first and second series of projections toward each other andthrough the web material at the locations of the crossing slits wherebyeach projection of one of said series of projections cooperates withprojections of the other of such series of projections which aredirectly adjacent thereto in deflecting from the original plane of theweb material and as planar units portions of the web material extendingbetween adjacent across slits in adjacent rows of crossing slits.

2. Apparatus as defined in claim 1 further including means for providinga continuous sheet with slits at spaced locations thereof correspondingto the spacing of the deflected portions of the web material, means fordisposing the slit sheet onto the defiected portions of the web materialso that parts therof project therethrough, and means for bending suchprojecting parts of the defiected portions of the web material tothereby lock the sheet in place.

3. Apparatus as defined in claim 1 further including means in advance ofsaid projections for cutting the web along lines extending betweenadjacent arms of each of the crossing slits to thereby remove arectangular section of web material therefrom and means positionedbeyond said projections for attaching a continuous sheet to theoutermost deges of the deflected portions of the Web material.

References Cited UNITED STATES PATENTS 1,927,791 9/1933 Balfe 29-16353,236,018 2/1966 Graham et al. 29-1635 2,009,963 7/1935 Matthael 29-4551,369,353 2/1921 Rabe 29-1635 BENJAMIN A. BORCHELT, Primary Examiner G.E. MONTONE, Assistant Examiner US. Cl. X.R. 29-1635, 455

ULYi-iLJU uinuuu luiunl Valle.

CERTlFlQATE 0F CGRREUHQN Patent No. 3 I v Dated Julv ll. l72

Inventor(s) Theodore lieirban'iis It is certified that error appears inthe above-identified patent and that said Letters Patent are herebycorrected as shown below:

Col. 3 line 34, "loouya'nt" should read ---louoyent. Col. 4-, line 60delete "a" (first occurrence) lines 72 75 "reaches of the belt 43 areportion of the film gtherebetween. should read ---the opposing beltreaches and "he portion of the film therebetween.-- Col. 5, line 1,Before 41" insert --reaehes of the belt 4-3 are longer than at of thebelt--7 line 35, delete "3%"; line 65, compositive" should read---composite., Col. 6, line 6, "91" should. read -lO"/ Claim 3., line38, "across" should read --crossing--. Claim 3, line 55, "deges" shouldread edges. In "References Cited, "liat hael" should read.--I=ia.tthaei-.

Signed and sealed this 2nd day of January 1975 (SEAL) Attest:

EDWARllM.FLETQHEK'JR" ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents

